Studies on Independent Synthesis of Cytoplasmic Ribonucleic Acids in Acetabularia mediterranea

1. The RNA content of anucleate and nucleate fragments of Acetabularia has been measured. It was found that there is a net synthesis of RNA in nucleate fragments. On the other hand, the RNA content of anucleate fragments did not change significantly after enucleation. 2. Anucleate fragments, however, can readily incorporate ¹⁴C-labeled adenine, orotic acid, and carbon dioxide into their cytoplasmic RNA. 3. The results of experiments on ¹⁴CO₂ incorporation into the RNA of anucleate and nucleate fragments suggest that there is a mechanism for de novo synthesis of RNA in anucleate cytoplasm. 4. In Acetabularia, 81 per cent of the cytoplasmic RNA is bound to a large granule fraction, consisting mainly of chloroplasts. Even after removal of the nucleus, RNA is synthesized in this "chloroplast" fraction. The chloroplasts are thus a major site of RNA synthesis in the cytoplasm of these algae. Synthesis of "chloroplastic" RNA, in anucleate fragments, possibly occurs at the expense of the RNA present in other fractions (microsomes and supernatant). 5. 8-Azaguanine stimulates regeneration and cap formation in anucleate fragments and does not inhibit RNA synthesis in these fragments.     

Germination of Aspergillus niger Conidia Is Triggered by Nitrogen Compounds Related to l-Amino Acids

Conidial germination is fundamentally important to the growth and dissemination of most fungi. It has been previously shown (K. Hayer, M. Stratford, and D. B. Archer, Appl. Environ. Microbiol. 79:6924–6931, 2013, http://dx.doi.org/10.1128/AEM.02061-13), using sugar analogs, that germination is a 2-stage process involving triggering of germination and then nutrient uptake for hyphal outgrowth. In the present study, we tested this 2-stage germination process using a series of nitrogen-containing compounds for the ability to trigger the breaking of dormancy of Aspergillus niger conidia and then to support the formation of hyphae by acting as nitrogen sources. Triggering and germination were also compared between A. niger and Aspergillus nidulans using 2-deoxy-d-glucose (trigger), d-galactose (nontrigger in A. niger but trigger in A. nidulans), and an N source (required in A. niger but not in A. nidulans). Although most of the nitrogen compounds studied served as nitrogen sources for growth, only some nitrogen compounds could trigger germination of A. niger conidia, and all were related to l-amino acids. Using l-amino acid analogs without either the amine or the carboxylic acid group revealed that both the amine and carboxylic acid groups were essential for an l-amino acid to serve as a trigger molecule. Generally, conidia were able to sense and recognize nitrogen compounds that fitted into a specific size range. There was no evidence of uptake of either triggering or nontriggering compounds over the first 90 min of A. niger conidial germination, suggesting that the germination trigger sensors are not located within the spore.     

Studies on Amino Acids

The enzymatic resolution of acetyl-dl-methonine previously reported was studied further, in detail. As a result, it was found that metal ion plays an important role on the asymmetric hydrolysis of acyl-dl-methonines by the enzyme preparations of Aspergillus oryzae.     

Piperidinyl Peptide Nucleic Acids: Synthesis and DNA-Complementation Studies

Abstract

Synthesis of a new six membered PNA analogue by introducing a methylene bridge between β carbon atom of ethylene diamine and β′ carbon atom of linker to nucleobase.     

Studies on Amino Acids XII.

Although acylase activities in animal tissues, molds, bacteria and yeast have been clarified, nothing has been reported on the acylase activity in plants. Therefore, as a part of a series of studies intending to elucidate the biological significance of the presence of acylase activity, activity in plants was investigated.

As a result, the occurrence of acylase activity in plants such as vegetables, potatoes, pulses, cereals and fruits, has been confirmed for the first time. Besides the above higher plants a relatively higher acylase activity was also found in mushroom.     

Studies on Amino Acids. II

The enzymatic procedures for the resolution of dl-lysine such as asymmetric synthesis of acyl l-lysinc anilide and acyl dl-lysines have been studied. As a result, the procedure consisting in the enzymatic asymmetric hydrolysis of ε-benzoyl-α-acctyl-dl-lysine was found to be the most advantageous for the resolution of dl-lysine.     

Studies on the Amino Acids Fermentation of Pentose Materials

Fundamental studies on the cultural conditions for the amino acids production from pentoses and hexoses employing a strain of our new isolates named Brevibacterium pentoso-aminoacidicum nov. sp. were carried out.

As a result of these experiments, it became possible to obtain about 30% of alanine and 10% of L-glutamic acid based on xylose, and alanine from glucose with a yield of about 40% in the proper conditions.     

Studies on the Amino Acids Fermentation of Pentose Materials

This work was undertaken to determine whether the degradation of sugars by Brevibacterium pentoso-aminoacidicum nov. sp., a bacterium capable of producing amino acids from pentoses and hexoses, was due to constitutive or inducible enzymes. It was also intended to clarify the reason for the substrate specificity in the fermentation of sugars by this bacterium. After a series of experiments using washed resting cells grown on various kinds of sugars or their cell-free extracts, it was found that the enzymes involved in the degradation of pentoses were inducible, while those of hexose metabolism were constitutive. The activities of several enzymes related to the pathways of pentose metabolism were demonstrated and the substrate specificity of sugar degradation by this strain was explained satisfactorily by the inducer specificity of these enzymes.     

Studies on the Decarboxylation of Amino Acids with Glyoxal

Decarboxylation of about twenty kinds of α, β and γ-amino acids in the reaction with glyoxal or ninhydrin was investigated. The decarboxylation rate of amino acids proved that steric and polar effects had important roles in the reaction.

From the data of pK₂ values and decarboxylation rates of amino acids, it can be concluded that under a similar steric environment, the decarboxylation rate depends on the anion concentration of amino acids.

Besides carbon dioxide, acetaldehyde, 2-propanone and propionaldehyde were respectively detected from the reaction of β-alanine, β and γ-amino-n-butyric acids with glyoxal or ninhydrin. The decarboxylation mechanism of these amino acids seemed to take place through the corresponding β- or γ-keto acid.

Oxygen absorption was also observed from the reaction of amino acids with dicarbonyl compounds.     

银杏酸单体的合成及构效关系研究进展

银杏酸的研究已经成为继银杏黄酮和内酯后的热点.本文综述了银杏酸同系物的结构及部分单体的合成研究进展,分析了合成路线,讨论了各合成方法的特点及适用性,并总结了银杏酸的结构和部分药理活性的关系.     

Studies on Amino Acids. IX.

The synthetic procedures for the preparation of α-keto acid analogue of methionine, α-keto-γ-methylmercaptobutyric acid, were investigated. As a result, the procedure consisting of the ester condensation between methyl β-methylmercaptopropionate and methyl oxalate, and subsequent hydrolysis and decarboxylation was found to be a satisfactory route     

Studies on Amino Acids. XI.

As a part of the studies intending to clarify biological significance of the presence of acylase, enzymatic activity which hydrolyzes acyl amino acids, its activity in yeast was investigated. As a results, the occurrence in yeast of acylase activity was confirmed for the first time.

In order to study the enzymatic properties of this acylase activity, experiments were carried out with the enzyme preparation from brewer’s yeast. As a result of the investigation, yeast acylase was found to be able to hydrolyze a number of acyl amino acids, of these chloroacetyl derivatives especially readily, as in the case of previously studied acylase activity in other sources such as mold acylase. Several observations on the influence of metal ions and inhibitors, optical specificity and others were also presented.     

二十二碳六烯酸和二十碳五烯酸研究进展(1)

二十二碳六烯酸（decosahexaenoic acid,DHA）和二十碳五烯酸（eicosapentaenoic acid,EPA）,是人、动物包括鱼体内的微量生物活性物质和必需的高度不饱和脂肪酸,在其繁殖、生长、发育过程中起非常重要的作用,从而吸引越来越多的研究者,取得了许多新进展。综述了EPA和DHA研究特别是代谢研究方面的最新成果．以促进应用和更好地把这些科学成果用于对鱼类与其他动物的深入研究。     

二十二碳六烯酸和二十碳五烯酸研究进展(2)

3 EPA和DHA的代谢 3．1 EPA和DHA的分解代谢天然不饱和脂肪酸多为顺式,需转变为反式构型,才能被β-氧化酶系作用,进一步氧化分解。在生物体内,不饱和脂肪酸的氧化需要更多酶的参与才能顺利进行,由于双键的存在,使DHA和EPA比饱和及单不饱和脂肪酸更难氧化分解。     

Solubilities Studies of Basic Amino Acids

The solbilities of l-basic amino acids in the type of free, monohydro-chloride and dihydrochloride in water were determined, and the results were formulated as follows.

l-Arginine: log S = 0.9770+0.01345t (t is from 0°~70°C)

l-Histidine: log S = 0.3627+0.00905t (t is from 0°~70°C)

l-Arginine monohydrochloride: log S = 1.6532+0.01301t (t is from 0°~70°C)

l-Lysine monohydrochloride dihydrate: log S = 1.6990+0.01294t (t is from 0°~55°C)

l-Lysine monohydrochloride monohydrate: log S = 1.7404+0.01256t (t is from 55°~70°C)

l-Lysine dihydrochloride: log S = 2.2138+0.00409t (t is from 0°~70°C)

l-Histidine dihydrochloride: log S = 1.9085+0.00265t (t is from 0°~70°C)

Three component systems (basic amino acid, hydrochloric acid, water) were studied and the solubilities in mixed solution system of alcohol-water were also investigated.     

xylo-Configured Oligonucleotides (XNA,Xylo Nucleic Acids): Synthesis and Hybridization Studies

Abstract

We report synthesis and high-affinity hybridization of fully modified home-thymine 2′-deoxy and 2′-deoxy-2′-fluoro xylo nucleic acids.